Pneumatic nailing machine



NOV. 7, 1967 RElCH ET AL PNEUMATIC NAILING MACHINE 5 Sheets-Sheet 2Filed April 21, 1967 MN w lnvenior:

NOV. 7, 1967 RElCH ET AL 3,351,257

PNEUMATIC NAILING MACHINE Filed April 21, 1967 5 Sheets-Sheet 3 I I Q I1 9\ K 256 28/ f 51/ f J 3; t 5/4 257 A 285 255 E49 lm emon' Mark 720 in1d Adolf CLKL Ev: Wu! MMMLi/ML A'fHJrnu United States Patent 3,351,257PNEUMATIC NAILING MACHINE Kurt Reich, Nurtingen, Wurttemberg, and AdolfCast, Oberlenningen, Wurttemberg, Germany, assignors to Karl M. ReichMaschinenfabrik Nurtingen, Wurttemberg, Germany Filed Apr. 21, 1967,Ser. No. 634,048 Claims priority, application Germany, Apr. 25, 1964, R37,776 14 Claims. (Cl. 227-130) ABSTRACT OF THE DISCLOSURE A pneumaticnailing machine which is provided with a percussion piston driven bycompressed air and guided in a working cylinder. The pressure chambertherein is connected through a bore in the wall of the working cylinderand through an air inlet valve with a compressed air supply line. Atubular slide valve surrounds the main cylinder and is movable to anopen position which closes a vent line communicating the bore with theouter air and permitting the compressed air to enter the pressurechamber and a closed position shutting olf the compressed air andopening the vent line, respectively.

This is a continuation-in-part application of the copending application,Ser. No. 449,705, filed Apr. 21, 1965, now abandoned.

The present invention relates to a pneumatic nailing machine which isprovided with a percussion piston, which may be driven by compressed airand is guided in a working cylinder, the pressure chamber of which isconnected through at least one opening in the wall of this cylinder andthrough an air inlet valve with a compressed-air supply line.

It is an oject of the present invention to provide a pneumatic nailingmachine which has an especially compact size and structural design, butstill insures that the air inlet valve will be opened very suddenly sothat the compressed air will drive the percussion piston forwardly withgreat force.

According to the invention, this object is attained by providing anannular chamber which surrounds the working chamber and is connectedwith the latter through a compressed-air inlet opening thereof, and isconnected with the compressed-air supply line at a point which isradially spaced from the outer surfaces of the working cylinder, and byproviding a tubular slide valve, which surrounds the cylinder and theannular chamber and extends coaxially thereto and is axially slidablealong the i1 ner wall of its valve housing, and which in its closedposition shuts off the compressed-air supply line from the inlet openingof the working cylinder. By providing the annular chamber around theworking cylinder, the advantage is attained, that this chamber may beconnected with the inside of the working cylinder through one or moreinlet openings in a manner, so as to permit the compressed air to enterthe working cylinder very rapidly and without restriction. Since thevalve member for shutting olf the supply of compressed air from theinlet opening of the working chamber also consists of a tubular slidevalve which surrounds the annular chamber, the further advantage isattained, that the inlet valve also has a very large cross-sectionalarea of flow. Furthermore, by providing this valve in the form of atubular slide valve around the working cylinder, it will not increasethe length of the nailing machine, while the increase in thickness ofthe nailing machine due to this tubular slide valve may be utilized forproviding the compressed-air supply line in the form of a tubularchannel, which like- 3,351,257 Patented Nov. 7, 19 67 wise surrounds thecylinder and forms an axial extension of the outer surface of the slidevalve or its housing. This arrangement of a tubular compressed-airsupply line also has the advantage that a very large cross-sectionalarea of flow of the compressed air through this supply line will beattained.

A very valuable feature of one preferred embodiment of the inventionfurther consists in providing the tubular slide valve in the form of adifferential piston, in which the piston part with the smaller endsurface is movable within a first pressure chamber which is connecteddirectly with the compressed-air supply line for moving the slide valveto its closed position, while the piston part with the larger endsurface is movable within a second pressure chamber which is connectedwith the compressedair supply line via an auxiliary valve for moving theslide valve to its open position.

Another advantageous feature of the invention provides that the tubularslide valve is composed of two sleeves which are screwed together by atubular connecting member in such a manner, that the mentioned endsurfaces form radial surfaces which are axially spaced from each otherand face each other, and that the side wall of the housing of the valveis provided with an inwardly projecting flange which extends between thetwo sleeves and the peripheral surface of which engages with the tubularconnecting member between the two sleeves and guides the slide valve,while the end surfaces of this intermediate flange together with theradial surfaces of the two sleeve parts define the mentioned first andsecond pressure chambers. The tubular slide valve may also be designedsuch, that one end thereof forms a sealing edge which, in case the valveis in its closed position, engages upon a valve disk of an elasticmaterial and thus insures r that this valve will be tightly closed, whenthe percussion piston is in its inactive or rest position.

The above-mentioned, as well as numerous other features and advantagesof the present invention will become more clearly apparent from thefollowing detailed description thereof, which is to be read withreference to the accompanying drawings, in which:

FIG. 1a shows a longitudinal section of the rear part or head of apneumatic nailing machine according to the invention, the tubular airinlet valve being in the open position and the percussion piston in theposition during its power stroke;

FIG. lb shows a longitudinal section of the rear part or head of apneumatic nailing machine according to the invention, the air inletvalve being in its closed position and the percussion piston in itsinactive or rest position;

FIG. 2 shows a longitudinal section of the main body of the same nailingmachine with the auxiliary valve in the actuated position and thepivotal nail feed conduit in the outwardly pivoted position, and withthe percussion piston in a position shortly before striking a nail;

FIG. 3 is a fragmentary section of a portion of the body at enlargedscale indicating the piston and the valve; and

FIG. 4 shows a longitudinal section of the rear part or head of anotherembodiment of the pneumatic nailing machine according to the invention.

Referring now to the drawings,and in particular to FIGS. l3, the rearpart of the pneumatic pistol-shaped nailing machine forms a head 1,which is secured to the main body 2 of the machine by means of a workingcylinder 3 of steel, which is provided with external screw threads 4 and5 on both ends. The screw thread 5 on the front end of cylinder 3 isscrewed into the socket-like rear end of a steel tube 6 around which anouter body 7 is cast which consists of a light-metal alloy, preferablyan aluminum or magnesium alloy. The front part of the steel tube 6contains the rear part of a short barrel-like mouthpiece 8 which isaxially slidable therein and prevented from falling out of the steeltube 6 by the provision of radial bores in the latter, into which balls9 are inserted, which engage into axially extending grooves 11 of ashort length and are held in this position by a rotatable ring 13 whichmay be locked by at least one spring-loaded ball 12. An axial movementof the ring 13 is prevented at one end thereof by the light-metal body 7and at the other end by a ring 14 which is secured on the steel tube 6by at least one screw 15 and carries a nail catcher 16. The mouthpiece 8is further provided with radial slots 17 containing clamping jaws 19which are pivotal about their rear axes 18 and are surrounded by aresilient ring 21 of plastic, so as to grip a nail 23 which is insertedinto the axial bore 22 in the mouthpiece 8.

For inserting the nails 23 into the bore 22, a nail feed line 24 isprovided which terminates into a separate tubular curved end part 25,which is pivotal back and forth about an axis 27 from a position withinthe nail channel 22, as shown in FIG. 2 in dot-and-dash lines, through aradial slot 26 in the lower side of the steel tube 6 and the body 7 tothe outside position, which is shown in full lines. In this outsideposition, the mouth of the tubular end part on the end of the nail feedline 24 is located opposite to the nail catcher 16, which is formed by aslot in a projection on the ring 13, so that any nails which areaccidentally fed, when the tubular end part 25 is in this outsideposition, will be caught by the nail catcher 16. In order to hold themouthpiece 8 in its forwardly advanced position, a spring 28 is providedacting upon a safety sleeve 29, which is mounted between a shoulder 31in the steel tube 6 and a collar provided on the safety sleeve 29. Inits forward side, the front end of this safety sleeve 29 is providedwith an axial slot, the bottom of which is inclined, so as to permit thecurved tubular end part 25 operating as a nail feed conduit, whenpivoted upwardly into the axial bore 22 operating as a nail channel, toengage partly into this slot. For holding this tubular end part 25 inthis position, it is provided with two lateral projections 32, whichengage into the front end of the sleeve 29, so that tubular end part 25will then be arrested by the safety sleeve 2-9 in the inwardly pivotedposition. If, however, the mouthpiece 8 is pushed back into the steeltube 6 when pressed against a workpiece 33, the safety sleeve 29 will atthe same time also be shifted toward the rear against the action of thespring 28, so that the projections 32 will then be released from thefront end of the sleeve 29 and the tubular end part 25 can pivot out ofthe bore 22 in the mouthpiece 8. The movement of the safety sleeve 29 inthe axial direction is limited by a pin 35 which engages into an axialgroove 34 in the sleeve 29.

For pivoting the tubular end part 25 on the end of the nail feed line24, a control valve piston 36 in the form of a differential piston isprovided in the grip 37 which is secured to the body 2 of the machine.The front end of a piston rod 38 of this valve piston 36 which projectsfrom the grip 37 is provided with a screw thread 39 on which two nuts 41are screwed between which a sleeve 42 is clamped which engages into abifurcated end 43 of the pivotal conduit or tubular end part 25. Whenthe control piston 36 is in its forward end position, it is possible toadjust the pivotal conduit or tubular end part 25 very accurately bymeans of the nuts 41, so as to be located in the proper position wit-binthe mouthpiece bore 22. Piston 36 is slidable within a valve cylinderwhich is formed by a bore in the grip 37. A working chamber 45 of thiscylinder adjacent to the larger end surface 44 of piston 36 is connectedby a channel 46 with an auxiliary valve 47, the slide member 48 of whichcarries on its outer end a push-button 49, while its cylindrical body isprovided with a continuous axial groove 51 and with sealing rings 52 and53 at both ends thereof. Slide member 48 is slidable within a guidebushing 55 which is screwed into a tapped bore 54 in the grip 37 and hasa radial aperture 56 therein which communicates with the axial groove 51and the channel 46 and is adapted to connect the channel 46 either withthe inner part of bore 54, when the slide member 48 is in the depressedor rearward position, as shown in FIG. 2, or with the outer air when theslide member is pushed outwardly, as shown in FIG. 3, that is, towardthe left of FIG. 2 of the drawing. The inner part of bore 54communicates through a channel 57 with a compressed-air supply line 58and through a channel 59 with a resetting chamber 61 of the valvecylinder for the control piston 36, so that in this chamber 61 alwaysthe same air pres sure prevails as in the compressed-air line 58.

The resetting chamber 61 is, in turn, connected with a valve chamber 62of a valve, the ball-shaped valve member 63 of which is normally pressedby a spring upon its seat, so as to close the chamber 62 toward the endof a conduit 64 which connects the valve 62, 63 with a nailfeedmechanism which is adapted to insert a nail into the nail feed line 24,when the connecting conduit 64 is vented. For lifting the valve ball 63off its valve seat,

a slide tappet 65 is provided, which projects into the working cylinder3 and will be depressed by a percussion piston 66, when the latterreaches the end of its power stroke in cylinder 3, so that thecompressed air can then pass from the valve chamber 62 into theconnecting conduit 64.

The connecting conduit 64 communicates through a bore 67 with a chamber68 which forms a narrower extension of the cylinder in which the controlpiston 36 is movable. The chamber 68 is connected at its rear end by avent channel 69 with the outer air, while its front end is sealedrelative to the sesetting chamber 61 by an extension 71 of the controlpiston 36. This extension 71,

which has a smaller diameter than the control piston 36 itself, isdesigned such as to close the bore 67 when piston 36 is in its rearwardposition, as shown in FIG. 2, and it will not open it toward the chamber68, until the control piston 36 has moved to the position, in which thepivotal nail conduit 25 engages into the mouthpiece bore 22. Thus, whenthe control piston 36 is in its inactive position, in which the end ofthe pivotal nail conduit 25 is held within the mouthpiece bore 22, theconnecting conduit 64 is vented, so that the nail-feed mechnaism (notshown) will then pass a nail into the nail feed line 24 and feed itthrough this line and the pivotal conduit 25 into the mouthpiece bore22. The rear end of the thinner part 71 of the controlpiston 36 carriesa rod 72 which engages upon a valve ball 73 which, when the controlpiston 36 is in its forward end position, is pressed by a spring 74 upona valve seat 75 and thereby shuts off the communication between achannel 76, which is connected to the compressed-air supply line 58, anda channel 77 which is connected by a line 78 to a pressure chamber 81 ofa cylinder bore in the head 1 (FIG. lb), in which the larger side 79 ofa tubular slide valve 82 in the form of a differential piston isslidable, which serves as a compressed-air inlet valve and in its closedposition shuts off a pressure chamber 83 of the working cylinder 3 fromcommunication with the compressed-air line 58.

When the control piston 36 is located in the position as shown in FIG.2, the valve ball 73, which forms the valve member of a second auxiliaryvalve, is lifted off its valve seat 75, so that the compressed airentering through the auxiliary valve 73, 75 into the pressure chamber 81of the cylinder containing the tubular slide valve 82 moves the latterto its open position. When the control piston 36 is in the position inwhich it maintains the end of the pivotal nail conduit 25 within themouthpiece bore 22, the rod 72 on the rear end of the piston 36disengages from the valve ball 73 so that the latter will be pressedupon its seat 75. Channel 77 is thereby shut off from the compressed-airline 58 and instead connected with the outer air through an axial bore84 and a transverse bore 85 in rod 72, the chamber 68, and the ventingchannel 69.

The nailing machine is further provided with two more cylinders 86 and87 which extend concentrically to cylinder 3 and form a tubular chamber88 and another tubular chamber 89, respectively. Chamber 88 is providedas an air storage chamber in which, through bores 113, the air is storedwhich is displaced by the percussion piston 66 during its power strokeand the air which has penetrated between the percussion piston and thewall of the work cylinder 3 in which this piston is loosely slidable.Thus, means for returning the percussion piston to its inactive positionare provided. In the present instance this stored air serves forreturning the percussion piston 66 to its inactive position after it hascompleted its power stroke and driven a nail 23 into the workpiece 33.The outer tubular channel 89 is directly connected with thecompressed-air line 58. The rear end of cylinder 86 is provided with aninwardly directed flange 91 which forms the end wall of the annularchamber 88 and carries a resilient sealing ring 92 upon which a sealingedge 93 on the tubular slide valve 82 is adapted to engage.

Slide valve 82 comprises two sleeves 94 and 95 which are screwedtogether and have radial surfaces '96 and 79 facing each other. Slidevalve 82 is separated from the work cylinder 3 by an annular chamber 97and it is slidable along and guided by a flange 99 which projectsinwardly from the valve housing 98 and the two end surfaces of which,together with the radial surfaces 96 and 79, respectively, define thefirst pressure chamber 101 and the second pressure chamber 81. The firstpressure chamber 101 is connected 'by grooves 102 and the tubularchannel 89 to the compressed-air line 58, so that, in the event thatthere is no pressure in the working-pressure chamber 81, the tubularslide valve 82 will be forced forwardly by the pressure prevailing inthe first pressure chamber 101, so that the sealing edge 93 of the slidevalve 82 will be pressed against the sealing ring 91. The radial surface96 is, however, smaller than the other radial surface 79, so that if thepressure in the second pressure chamber 81 is equal to that in the firstpressure chamber 101, the

slide valve 82 will be shifted to its open position, as shown in FIG.1a.

The percussion piston 66 is locked in its inactive position by aresilient locking member 103 which is shaped somewhat like a mushroomand then engages into a socketrecess 106 is provided for receiving therear end of the slide valve 82, when it is in its open position. As longas this end of the slide valve 82 is not located within the annularrecess 106, this recess communicates through a gap 108 with a channel109 which, in turn, is connected through an adjustable needle throttle110 with a channel 111 which leads to the outer air, so that when theslide valve 82 is in its closed position, the pressure chamber 83 ofwork cylinder 3 communicates through the bores 105, the recess 106, andthe channels 109 and 111 with the outer air.

The operation of the nailing machine according to the present inventionis as follows:

When in the inactive or rest position of the nailing machine thecompressed-air line 58 is connected to a source of compressed air, butthe first auxiliary valve 47 is not as yet actuated, the slide member 48of this valve, as shown in FIGS. 2 and 3, will be held in its left outerposition, in which the sealing ring 53 seals off the groove 51 from thecompressed air prevailing in the bore 54 and groove 51 communicates withthe outer air since the sealing ring 52 is lifted off the guide bushing55. The work chamber 45 for the control piston 36 is then also connectedwith the outer air through the channel 46 so that, due to the pressureprevailing in the resetting chamber 61, because of its connectionthrough the channels 59 and 57 with the compressed-air line 58, thecontrol piston 36 will be held in its inactive position in which itmaintains the end of the pivotal nail conduit 25 in the position asindicated in FIG. 2 in dot-and-dash lines, in which this end engagesinto the mouthpiece bore 22. The second auxiliary valve 73, 75 is thenlikewise closed, so that the second Working-pressure chamber 81 of slidevalve 82 is connected with the outer air through the line 78, bores 84and in rod 72, and the vent channel 69. However, since the firstpressure chamber 101 is connected through the grooves 102 and thetubular channel 89 with the compressed-air line 58, slide valve 82 willbe held in its closed position, as shown in FIG. 1b by the pressurewhich acts upon its smaller radial surface 96.

If the push-button 49 on valve 47 is then depressed by the operator ofthe machine, groove 51 will no longer be connected with the outer air,since the sealing ring 52 will then engage with the guide bushing 55,but the compressed air in the bore 54 will then penetrate through thegroove 51 and the channel 46 into the working chamber 45 of the cylinderof the control piston 36. Since the end surface 44 of the control pistonis larger than its other end surface facing the resetting chamber 61,the control piston 36 will then be moved to the position as shown insolid lines in FIG. 2. At the same time, the nail conduit 25 will bepivoted out of the mouthpiece bore 22 and the valve ball 73 will belifted, off the valve seat 75 by the rod 72. This permits the compressedair to pass through the channels 76 and 77 and the line 78 into thesecond pressure chamber 81 of the tubular slide valve 82, so that thisvalve will be moved to its open position, as shown in FIG. 1a. Thecompressed air will then pass suddenly from the annular chamber 89through the annular chamber 97 and the bores into the pressure chamber83 of the working cylinder 3. and act upon the percussion piston 66, sothat the latter will carry out its power stroke and its striker rod 112will hit upon the head of the nail 23 in the mouthpiece bore 22 intowhich -it has previously been inserted and will drive it into theworkpiece 33. As soon as the percussion piston 66 reaches the end of itspower strike, it depresses the tappet 65 of 'valve 63, so thatcompressed air will then pass through the connecting line 64 to thenail-feed mechanism, whereby the next nail will be moved into a positionready to be fed to the machine.

As soon as the operator of the machine then releases the push-button 49,the pressure in the bore 54 will move the slide member 48 of theauxiliary valve 47 back toward the left to its original position, sothat the work chamber 45 of the control piston 36 will be vented and thepressure prevailing in the resetting chamber 61 will move this pistonback to its inactive position and thereby pivot the nail conduit 25 intothe mouthpiece bore 22 to the .position as indicated in dot-and-dashlines in FIG. 2. At the same time, the valve ball 73 of the secondauxiliary valve will be pressed by its spring 74 upon its seat 75. Thebores 84 and 85 in rod 72 are then also connected with the vent channel69, so that the second pressure chamber 81 of the tubular slide valve 82will be vented through the line 78, the channel 77, the bores 84 and 85,and the vent channel 69 with the result, that the pres sure which thenacts upon the radial surface 96 of slide valve 82 and upon its rearsurface which is located in the annular recess 106 in the cap 107 willmove the slide valve 82 to its closed position, as shown in FIG. 1b. Assoon as slide valve 82 reaches its closed position, gap 108 is openedand the pressure chamber 83 of the work cylinder is vented through theneedle throttle 110 sothat, since the annular chamber 88 communicatesthrough the bores 113 with the chamber of the working cylinder in .frontof the percussion piston, the air which has been 7 stored up in chamber88 will then drive the percussion piston 66 back to its rest position inwhich itwill be held by the locking member 103.

Also at the same time, when the control piston 36 moves toward the left,the rear part 71 thereof uncovers the bore 67, so that the connectingline 64 is likewise vented, whereby the nail feed mechanism is actuatedto feed the next nail through the nail feed line 24 and the pivotalconduit 25 into the mouthpiece bore 22. As soon as this has occurred,the push-button 49 may again be depressed, whereupon the entire cycle ofoperations, as above described, will be repeated.

Since the needle throttle 110 is adjustable, it permits the discharge ofthe air from the pressure chamber 83 to be regulated, so as to preventthe percussion piston 66 from being driven back to its rest positionwith such a force, that it might rebound from the end wall of the workcylinder 3 and become unlocked from the locking member 103.

Referring now again to the drawings, and more particularly to FIG. 4, inthis embodiment, a slide valve 282 is provided in a second annularchamber 281 which is directly adjacent and connected with a controlvalve 247 via a short channel 278. The channel 278 is as short aspossible due to the adjacent location of the second annular chamber 281and the control valve 247 for venting of the second annular chamber 281as will hereinafter become apparent. The piston rod 238 of the valve 247projects from below grip 237 and its outer end abuts a push button 249,the latter being swingable about axis 227. The piston rod 238 carries apiston 236 which is axially displaceable in the bore of a second piston236 which is axially displaceable within the housing of the valve 247.The piston 236 has two bores 276 and 277, respectively, which, in thefirst rest position of the piston 236, connects a compressed air supplyline 258 with the channel 278, and thus with the second annular pressurechamber 281. The slide valve 282 is maintained in its closed position bythe pressure in the chamber 281. In this position, the sealing edge 293of the slide valve 282 abuts sealing ring 292 and thus prevents thecompressed air from penetrating from a first annular pressure chamber301 through bores 305 in the main cylinder 203 into pressure chamber283. In this position of the slide valve 282, the pressure chamber 283is connected to the outside air via annular chamber 297, bores 208 inthe slide valve 282 and bores 209 (or vent line) in the valve housing298.

Upon pressing the push-button 249, the piston rod 238, and thus thepiston 236, is moved to its second position, in which the compressed airchannel formed by the bores 276 and 277, respectively, is sealed andclosed by the upper end of the piston 236. Upon further pressing of thepush-button 249, the second piston 236' is moved upwardly, so that itslower edge forming sealing edge 310 is lifted from a sealing ring 311.By this arrangement, the channel 27 8, and thus the second annularpressure chamber 281, is connected to the outside air via annularchambers 312 and 312 as well as bores 313 and 314. The compressed airthus escapes from the second annular pressure chamber 281, and the slidevalve 282 is moved by the compressed air acting on its upper smallerface 296 from the first annular pressure chamber 301 into its openposition. In this position, the bore 208 closes so that the compressedair cannot escape from the pressure chamber 283. In order to achieve atight sealing, the slide valve 282 is equipped at its periphery with anannular projection 316 which abuts a shoulder 317 of the valve housing298 when the slide valve 282 is in its open position. A tight seal ofthe bores 208 towards the outside is thus obtained.

The slide valve 282 is preferably made from an acetal resin known by thetrade name Delrin or the like. It can be manufactured very economically,since there is no finishing required after the injection molding. Inaddition, it is very sturdy and has a good resistance against wear andtear and thus a long active life. The sliding properties of the plasticslide valve 283 on the cylinder 203 are very good. Finally, the abutmentof the annular projection 316, made from acetal resin, against the metalshoulder 317 provides a very tight seal.

In the percussion piston 266, a bore 315 is provided connecting thepressure chamber 283 with an annular space in the main chamber of thecylinder 203, the annular space being arranged peripherally at the frontof the percussion piston 266. The diameter of the bore is so small thatthe compressed air streaming therethrough during the stroke of thepercussion piston 266 does not harnper the movement of the latter. Thebore 315 also serves the purpose of feeding additional compressed airthrough the bore 213 into the annular chamber 288 at the completion ofeach stroke performed by the percussion piston 266, in addition to theair displaced by the percussion piston. After closing of the slide valve282 and after venting of the pressure chamber 288, the percussion piton266 is then moved into its position of rest. In order to prevent arubber-elastic stopper 318 for the percussion piston 266 from movinginto the bore 315 during an idle stroke, the bore is projected radiallyoutwardly at the recessed periphery of the front side 319 of thepercussion piston 266.

While we have disclosed several embodiments of the present invention, itis to be understood that these embodiments are given by example only andnot in a limiting sense, the scope of the present invention beingdetermined by the objects and the claims.

We claim:

1. A pneumatic nailing machine comprising a main cylinder defining amain chamber,

a percussion piston slidable within said main cylinder in the axialdirection thereof,

said main cylinder having a pressure chamber behind said piston as apart of said main chamber,

at least one bore in the Wall of said main cylinder opening into saidpressure chamber,

a tubular slide valve surrounding said main cylinder,

a compressed air supply line controlled by said tubular slide valve,

means for communication between said compressed air supply line and saidbore in response to the position of said tubular slide valve,

a vent line communicating said bore with the outer air for venting saidpressure chamber, said tubular slide valve being axially movable alongsaid main cylinder between two positions, from a first position in whichsaid tubular slide valve closes said vent line and compressed air passesinto said pressure chamber, thereby acting upon the rear end of saidpercussion piston to carry out a forward power stroke, to a secondposition in which said tubular slide valve opens said vent line andinterrupts the flow of compressed air to said pressure chamber, and

means for returning said percussion piston to its inactive position.

2. The pneumatic nailing machine, as set forth in claim 1, wherein saidmeans for returning said percussion piston comprises a cylindersurrounding said main cylinder in spaced relation and forming therewithan annular chamber communicating with said main chamber and defining anair storage chamber to receive air from said main chamber to return saidpercussion piston to its inactive position.

3. The pneumatic nailing machine, as set forth in claim 1, wherein saidtubular slide valve has a larger radially extending surface and asmaller radially extending surface, said surfaces are axially spacedapart from each other,

a valve housing radially spaced from said main cylinder for receivingsaid tubular slide valve and having an inwardly projecting flangethereon,

said flange together with said smaller and said larger radiallyextending surfaces defines a first and a second annular pressurechamber, respectively,

said first annular pressure chamber being connected to said compressedair supply line,

a control valve connected at one side to said compressed air supply lineand at the other side to said second annular pressure chamber, and beingmovable between a first and a second position,

said control valve in its first position allowing the compressed air toflow into said second annular pressure chamber to act on said tubularslide valve to move it into one of its two positions, and

said control valve in its second position venting said second annularpressure chamber, so as to permit said slide valve to move under thepressure on said smaller surface into the other of its two positions.

4. The pneumatic nailing machine, as set forth in claim 3, wherein 3,wherein said first annular pressure chamber is located at the upper endof said tubular slide Valve surrounding the top of said main cylinderand connected directly with said compressed air supply line.

6. The pneumatic nailing machine, as set forth in claim 3, whichincludes a main body receiving said control valve, said main cylinder isconnected near its front end to said body and projects toward the rearthereof, a barrel-like mouthpiece has a rear part secured within saidbody and a front part projecting therefrom, said mouthpiece has an axialbore in axial alignment with said main cylinder,

a nail feed channel within said body, and

the rear end of said channel is adapted to be connected to a nail feedmechanism separate from said machine and its forward end is adapted tocommunicate with said axial bore of said mouthpiece to permit a nail tobe conveyed through said nail feed channel into said mouthpiece bore.

7. The pneumatic nailing machine, as set forth in claim 6, furthercomprising means connected to the front part of said machine forcatching a nail, if propelled from said nail feeding channel, if theforward end of the latter is not in communication with said axial boreof said mouthpiece.

8. The pneumatic nailing machine, as set forth in claim 1, wherein saidtubular slide valve is disposed in spaced relation from said maincylinder and forms with the latter a first annular chamber, and saidfirst annular chamber constitutes said communication means. 9. Thepneumatic nailing machine, as set forth in claim 8, wherein said maincylinder is surrounded by a second annular chamber, said tubular slidevalve being disposed in said second annular chamber,

said compressed-air supply line is connected to said second annularchamber at a point radially spaced apart from the outer surface of saidmain cylinder, and said tubular slide valve divides said second annularchamber into a radial outer part connected with said compressed-airsupply line and said first annular chamber connected with said inletopening. 10. The pneumatic nailing machine, as set forth in Claim 1,further comprising an adjustable throttle member disposed within saidvent line.

11. The pneumatic nailing machine, as set forth in claim 1, comprising amain body,

said main cylinder is secured at its front end into said main body andprojects toward the rear thereof,

a barrel-like mouthpiece has a rear part secured to and axially slidablewithin said main body and in axial alignment with said main cylinder,and

spring means acting upon said mouthpiece and tending to press the sameforwardly.

12. The pneumatic nailing machine, as set forth in claim 1, wherein saidtubular slide valve is made of plastic material.

13. The pneumatic nailing machine, as set forth in claim 1, wherein saidplastic material is acetal resin.

14. The pneumatic nailing machine, as set forth in claim 12, wherein 40said tubular slide valve includes at its periphery an annular rojection,and a valve housing radially spaced about said main cylinder forreceiving said tubular slide valve and having an inwardly projectingshoulder thereon adapted to abut said annular projection sealingly whensaid tubular slide valve is in said first position and providing atight-seal between said bore and said vent line.

References Cited UNITED STATES PATENTS 3,010,430 11/1961 Allen et al.3,172,124 3/1965 Kremiller 227- X 3,301,456 1/1967 Schafroth et a1.227130 X 50 GRANVILLE Y. CUSTER, 1a., Primary Examiner.

1. A PNEUMATIC NAILING MACHINE COMPRISING A MAIN CYLINDER DEFINING AMAIN CHAMBER, A PERCUSSION PISTON SLIDABLE WITHIN SAID MAIN CYLINDER INTHE AXIAL DIRECTION THEREOF, SAID MAIN CYLINDER HAVING A PRESSURECHAMBER BEHIND SAID PISTON AS A PART OF SAID MAIN CHAMBER, AT LEAST ONEBORE IN THE WALL OF SAID MAIN CYLINDER OPENING INTO SAID PRESSURECHAMBER, A TUBULAR SLIDE VALVE SURROUNDING SAID MAIN CYLINDER, ACOMPRESSED AIR SUPPLY LINE CONTROLLED BY SAID TUBULAR SLIDE VALVE, MEANSFOR COMMUNICATION BETWEEN SAID COMPRESSED AIR SUPPLY LINE AND SAID BOREIN RESPONSE TO THE POSITION OF SAID TUBULAR SLIDE VALVE, A VENT LINECOMMUNICATING SAID BORE WITH THE OUTER AIR FOR VENTING SAID PRESSURECHAMBER, SAID TUBULAR SLIDE VALVE BEING AXIALLY MOVABLE ALONG SAID MAINCYLINDER BETWEEN TWO POSITIONS, FROM A FIRST POSITION IN WHICH SAIDTUBULAR SLIDE VALVE CLOSES SAID VENT LINE AND COMPRESSED AIR PASSES INTOSAID PRESSURE CHAMBER, THEREBY ACTING UPON THE REAR END OF SAIDPERCUSSION PISTON TO CARRY OUT A FOWARD POWER STROKE, TO A SECONDPOSITION IN WHICH SAID TUBULAR SLIDE VALVE OPENS SAID VENT LINE ANDINTERRUPTS THE FLOW OF COMPRESSED AIR TO SAID PRESSURE CHAMBER, ANDMEANS FOR RETURNING SAID PERCUSSION PISTON TO ITS INACTIVE POSITION.